Biphasic cuirass ventilation
Biphasic cuirass ventilation (BCV) is a non-invasive method of negative pressure ventilation which requires the patient to wear an upper body shell or cuirass.
Biphasic cuirass ventilation was developed by Zamir Hayek, a pioneer in the field of assisted ventilation. Some of Hayek's previous inventions include the Hayek Oscillator, an early form of the technology.
As the ventilation provided by the cuirass is biphasic, it is possible to achieve both normal breathing (tidal volumes) and a high respiratory rate (from 6 to 12[1] breaths per minute). The biphasic function allows control over the I:E ratio, which is the ratio between the time allowed for inspiration (pumping air out of the cuirass and creating a negative pressure around the chest) and expiration (pumping air into the cuirass and creating an increase in pressure around the chest.) Most other types of ventilation depend on the passive recoil of the patient's chest, which limits the respiratory rate.
Uses
BCV has been successfully used on patients with:
- Acute respiratory failure
- Chronic obstructive pulmonary disease (COPD)
- Neuromuscular (e.g., SMA, Duchennes, etc.)
- Head and spinal injuries
- Problems with weaning from positive pressure ventilation (PPV)
- Ventilation during anesthesia in ear, nose, and throat (ENT) procedures
- Cystic fibrosis (CF), and those who require physiotherapy
- AIDS related lung disease
- Asthma
- Ventilation post-operation (e.g., post-coronary bypass, Fontan, Fallot, post-pneumonectomy)
- Ondine's curse
Advantages
BCV is non-invasive and therefore avoids some of the problems associated with invasive ventilation such as infection and barotrauma. Unlike intermittent positive pressure ventilation (IPPV), BCV is active in both the inspiratory and expiratory phases (biphasic). This allows greater control over the tidal volumes and respiratory rate. BCV may also help to maintain and redevelop the respiratory muscles which may weaken with respiratory failure and mechanical ventilation,[citation needed] this allows patients to be weaned from a ventilator. BCV also does not impair cardiac function, as IPPV does. BCV is often used as an aid in patients with poor cardiac output.
Unlike conventional negative pressure ventilation, biphasic cuirass ventilation is able to quickly reduce any harmful buildup of CO2 using its active expiratory phase. Many published papers and case studies now show how effective BCV is at reducing CO2 buildup. It has also now been shown that the most effective ventilation frequency to reduce CO2 when using BCV is 60 cycles per minute.[2] The oscillations caused by BCV assist in the removal of secretions which are a symptom of many respiratory diseases. Lastly, because BCV does not require the patient to be intubated or to have a tracheostomy, patients can have BCV at home.
BCV has also been successfully used in a case of failed fiberoptic intubation,[3] in microlaryngeal surgery,[4] and after pediatric cardiac operations.[5][6]
Disadvantages
BCV has limited effect on patients who suffer from extreme obesity. BCV requires patients to maintain their own patent airway (patients with Obstructive Sleep Apnea may require additional assistance from positive pressure ventilation to open the airway). BCV should not be used on open wounds or burn victims.
See also
References
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